Optical system for electric arc furnaces



mum HEBERUWK. oLHnun nu| Feb. 27, 1968 P. J. WYNNE OPTICAL SYSTEM FORELECTRIC ARC FURNACES 3 Sheets-Sheet 1 Filed Nov. 9, 1964 INVENTOR.Peter J ZZ flne Feb. 27, 1968 P. J. WYNNE OPTICAL SYSTEM FOR ELECTRICARC FURNACES Filed Nov. 9, 1964 5 Sheets-Sheet 2 Feb. 27, 1968 P. J.WYNNE OPTICAL SYSTEM FOR ELECTRIC ARC FURNACES 5 Sheets-Sheet Filed Nov.9, 1964 INVENTOR. Peter J Z/yzme fittarmgy United States Patent3,371,140 OPTICAL SYSTEM FOR ELECTRIC ARC FURNACES Peter J. Wynne,Pittsburgh, Pa., assignor to McGraw- Edison Company, Milwaukee, Wis., acorporation of Delaware Filed Nov. 9, 1964, SeraNo. 409,661 15 Claims.(Cl. 13-9) This invention relates to optical systems for electric arcfurnaces and, more particularly, to an optical system for a controlledatmosphere consumable electrode type electric arc furnace.

Consumable electrode electric arc furnaces have been widely used forsuch applications as the melting of refractory metals, of which titaniumis an example. Such furnaces, in general, include a sealed chamberwherein a consumable electrode is progressively melted under acontrolled atmosphere and the resulting molten metal collected in acrucible to form an ingot. Melting is accomplished by means of an arewhich is drawn between the consumable electrode and the ingot, and whichis sustained by relatively large direct currents. As the ingot forms,the electrode length gradually decreases so that it must be lowered inorder to maintain the proper arc length for the desired meltingconditions. For this purpose, a motor-driven electrode ram is providedfor feeding the electrode toward the ingot, in accordance with theelectrical conditions in the arc. After the electrode has beencompletely consumed, the ingot must first be allowed to cool and then beremoved from the crucible prior to the initiation of another meltingoperation. Because a relatively long time is required for such ingots tocool, it is desirable that a single electrode drive and ram assembly bemounted for successive operation over several crucibles.

In most melting applications, it is necessary to observe the are atvarious times during a melting operation. For this reason, most priorart controlled atmosphere, consumable electrode arc furnaces wereprovided with fixed sight tubes for viewingalong the electrode and inthe gap between the electrodeand the crucible. Prior art sight tubeswere not wholly satisfactory, however, because the gap between theelectrode and the crucible varies consider ably even where theelectrodes are nominally of the same size. This is additionallycomplicated by the fact that consumable electrodes employed in this typeof furnace are generally in the order of twelve feet in length and mayhave surface irregularities. Prior art sight tubes were additionallyunsatisfactory Where various size electrodes were employed, because theycould not penetrate sulficiently close to the electrode ram to viewalong the surface of smaller-sized electrodes.

In controlled atmosphere, consumable electrode vacuum arc furnaceinstallations, the arc image is generally pro jected on an operatorviewing screen. Prior art optical systems could not be employed,however, in installations having a single electrode drive assembly and aplurality of crucibles.

It is an object of the invention to provide a new and improved opticalassembly for controlled atmosphere, consumable electrode, electric arcfurnaces.

A further object of the invention is to provide an optical assemblycapable of viewing along the gap between the electrode and the crucibleof controlled atmosphere, consumable electrode, arc furnaces regardlessof electrode size and surface irregularities.

Another object of the invention is to provide an optical system for usewith consumable electrode arc furnaces having a single electrode driveassembly and a plurality of spaced apart crucibles.

A still further object of the invention is to provide an arc meltingfurnace having a plurality of vessels, elec I 3,371,140 Patented Febo27,, 1968 ice trode means for being selectively positioned over thevessels and an optical system having a first light modify= ing meansmounted on the electrode means for receiv= ing the arc image ray and forprojecting the same to viewing means when the electrode means is overone vessel and second light modifying means for receiving the projectedray and for transmitting the same to the view= ing means when theelectrode means is over a second vessel.

Yet another object of the invention is to provide in an electric arcfurnace an optical assembly rotatably mounted about an axis generallyparallel with the electrode and including tube means disposed at apredetermined angle relative to the axis of rotation and having firstlight modi= fyirig means for redirecting arc image rays along the axisof the tube means and fixedly mounted second light modi= fying means forreceiving the projected rays and for re= directing them at a preselectedangle.

These and other objects and advantages of the instant invention willbecome more apparent from the detailed description thereof taken withthe accompanying draw= ings in which:

FIG. 1 is a side elevational view, partly in section, of a controlledatmosphere, consumable electrode, electric arc furnace whichincorporates the optical assembly accord= ing to the instant invention;

FIG. 2 is a side elevational view, partly in section, of a portion ofthe optical assembly illustrated in FIG. 1;

FIG. 3 is a view taken along lines 33 of FIG. 2;

FIGS. 4 and 5 are respectively a top plan view and a side elevationalview schematically illustrating the op-= eration of optical systemaccording to the instant inven-= tion, and

FIG. 6 is a perspective view of another portion of the optical systemillustrated in FIG. 1.

Referring now to the drawings in greater detail, FIG. 1 shows aconsumable electrode, controlled atmosphere, electric arc furnacedesignated by the reference numeral 10 and having a crucible section 11,a middle section 12 and an electrode drive assembly 13.

The crucible section 11 includes an outer, substantially cylindricalshell 15 having a bottom closure member 16 which is suitably afiixedthereto in a sealed relation to provide a cooling jacket for a crucible22 disposed therein and which receives an ingot 23 formed from the metalbeing melted. Cooling fluid is supplied to the shell 15 through inletand outlet pipes 24 and 25, respectively. A horizontal base plate 26 issupported adjacentthe upper end of shell 15 by vertical columns 28 andhas a central aperture 29 for receiving the upper end of the crucible22. A gasketed flange 32 extends outwardly from the upper end of thecrucible 22 and is suitably afiixed to the upper surface of the mountingplate 26.

The middle section 12 of the furnace 10 includes a lower middle section36, an upper middle section 37 and an upper middle section driveassembly 38. The lower middle section 36 has a generally cylindricalconfiguration which is cordial with the crucible 22. An outwardlyextending flange 39 at the lower end of lower middle sec tion 36 issuitably aflixed to the flange 32 on crucible 22.

The upper middle section 37 which is an inverted, cup= shaped memberforms a closure for the hollow assembly 45 consisting of the crucible22, the lower middle section 36 and the upper middle section 37., Asuitably gasketed flange 41 extends outwardly from the lower end of theupper middle section 37 and is releasably securable to a. correspondingflange 42 on the upper end of the lower middle section 36 by means ofbolts 43.

An electrode 46 is disposed within the hollow assembly 45 and has a stub48 integrally formed at its upper end for releasable attachment to thebottom of a hollow elec= trode ram 49 by a clamp 50. The ram 49 slidablypasses through a sealing bushing 56 which provides a fluid-tight sealfor the enclosure 45 and, in addition, electrically insulates ram 49from the upper middle section 37.

A pipe 57 is connected to and communicates with the interior of theenclosure 45 for placing the latter in communication with an evacuatoror source of inert gas it a partial vacuum or inert gas atmosphere isrequired during the melting operation.

A. generally rectangular base plate 60 is disposed above the uppermiddle section 37 and is mounted on the upper ends of first and secondframe members 61 and 64, respectively. The lower end of member 61 issupported in a pair of wheels 62, which engage the upper surface of theplate 26 and the lower end of the second frame member 64 engages arotary hydraulic cylinder 63 whose pur pose will be explained in greaterdetail hereinbelow. The plate 60 supports the upper middle section driveassembly 38 and the electrode drive assembly 13.

The electrode drive assembly 13 is supported above the base plate 60 byvertically extending rods 65 whose iower ends are aflixed to the plate60 and whose upper ends support a top plate 66. The drive assembly 13also includes a first plate 68 which is affixed to the upper end of theelectrode ram 49 and a second plate 70 disposed vertically above theplate 66 and having a nut 71 affixed in an aperture formed therein andconcentric with the ram 49. A tubular member 74 is slidably disposed oneach of the support rods 65 and each is aflixed at its lower end to thefirst plate 68 and at its upper end to the second plate 70 so that theplates 68 and 70 are coupled for sliding vertical movement on thesupport rod 65.

The electrode drive assembly 13 also includes a motor 76 suitablymounted on the upper plate 66 and a drive screw 77 which threadablyengages the fixed nut 71 in the second plate 70 and extends verticallydownward through apertures 78 and 80 in the plates 66 and 68, re-=spectively, and into the hollow interior of the electrode ram 49. Apinion 81 is carried on the output shaft 82 of: the motor 76 and engagesa gear 84 affixed to the upper end of the screw shaft 77 and rotatablymounted about the aperture 78 in the plate 66 by a suitable bearingassembly 85.

Electrical energy is supplied to the electrode 46 through a terminal 88mounted on plate 68 and which is constructed and arranged to receive aflexible conductor 89. Current flows from the plate 68 through theelectrode ram 49, the clamp 50, the stub 48 and to the electrode 46.Bushings 90, of any suitable insulating material, insulate the guiderods 65 from the plates 68 and 70 and the tubes 74.

The upper middle section drive assembly includes a motor 92 suitablymounted on the base plate 60 and a pinion 93 afi'ixed to the motoroutput shaft 94. Pinion 93 engages a ring gear 96 which is rotatablymounted by means of a bearing (not shown) on a bushing 98 disposed in anaperture 100 formed in the support plate 60. The bushing 98 slidablyreceives the electrode ram 49 and electrically insulates it from thebase plate 60. Three small gears 102 engage the ring gear 96 atapproximately 120 intervals and each is rotatably mounted in bearings105 disposed in corresponding apertures 104 formed in the plate 60. Eachof the small gears 102 has a suitable internal threaded aperture forengaging the upper end of a screw shaft 108, the lower end of which iscoupled to the upper surface of the upper middle section 37 by auniversal coupling 110.

The electrode drive assembly motor 76 may be of the reversible, variablespeed, DC type, which is controlled in accordance with electrode voltageand current conditions. The motor control, which is not shown but iswell known in the art, causes the motor 76 to rotate in a directionwhich maintains the are between the electrode 46 and the ingot 23 at arelatively uniform length. Thus, when the arc length is too short, themotor will rotate the screw shaft 77 in a first direction through thepinion 81 and the gear 84. This moves the nut 7.1, and the plate 70 towhich it is affixed upwardly relative to the shaft 77. The electrode ram49 which is rigidly coupled to the plate 70 by the plate 68 and thetubes 74 also moves upwardly to raise the electrode 46. Conversely, whenthe arc length is too long the motor 76 will rotate the shaft 77 in anopposite direction to lower the electrode 46. However, since theelectrode 46 has a smaller diameter than the crucible 22, "the generaldirection of movement of the electrode will be downward during a meltingoperation.

After the electrode 46 has been melted so that substan= tially only thestub 48 remains. the electrode drive as sembly 13 is positioned abovethe alternate crucible 22 while the ingot 23 is allowed to cool. Forthis purpose. the motor 76 is driven in a direction which raises theclamp 50 to its uppermost position in the chamber 45. The bolts 43 arethen removed to release the upper middle section 37 from the lowermiddle section 36. Motor 92 is then operated to rotate the gears 102through the agen cy of the pinion 93 and the ring gear 96 in a directionwhich raises each of the screw shafts 108. As a result, the upper middlesection 37 is raised to a position. free of the lower middle section 36.The motor 76 is then reactuated in a direction which raises electrodeclamp 50 and the stub 48 to a position above the upper flange 41 of thelower middle section 36. The rotary hydraulic cylinder is then actuatedto pivot the base plate 60 and the frame member 61 and 64 to a positionabove an alternate crucible as the wheels 62 roll on the base plate 26.After the electrode drive assembly 13 has been positioned above thealternate crucible 22, the electrode ram assembly 49 is lowered untilthe clamp 50 is in a position to be secured to the stub on the electrodewhich was previously disposed within said alternate crucible. The motor92 is then operated in a direction which lowers the upper middle section37 until it is in a position to be secured to the flange on the lowermiddle section of the alternate crucible 22', whereby melting may beginin said alternate crucible while the ingot 23 in the first crucible 22cools.

The optical system, according to the instant invention, is shown inFIGS. 1, 4 and 5 to include a pair of optical assemblies 120, one ofwhich is mounted on each of the opposite sides of the upper surface ofthe upper middle section 37 and adjacent the opposite sides of thebushing 56. The optical system also includes a mirror assembly 121, afirst lens 122 and a second lens 123 associated with each of the opticalassemblies 120. 'Each of the optical. assemblies along with itsassociated mirror assembly 121, first lens 122 and second lens 123transmits an image of the are at its side of the electrode to anoperator viewing screen 124.

The optical assembly 120 is shown in FIG. 2 to be mounted in an aperture129 formed in the upper end of the upper middle section 37 and adjacentthe bushing 98 by means of a plurality of clamping blocks 130 and screws131, only one set of which is seen in FIG. 2. The clamping blocks 130engage the upper surface of an optical assem= bly base plate 133 toforce an outer peripheral flange 134 on said plate against a shoulder136 formed in. the periphcry of the aperture 129.

The optical assembly 120 is shown to include a first mirror 138, asecond mirror 139, a lens 140 and a reflect.- ing prism 142. The lens140 is disposed at the junction of a pair of hollow, open-endedcoaxi-ally' disposed and C0-- radial mirror support tubes 144 and 145.One end of each of the tubes 144 and 145 is cut at a substantially 45angle and is recessed for receiving one of the mirrors 138 and 139,respectively. The mirrors 138 and 139 are held in position by means ofmirror support plates 147, which are suitably afiixed to the remote endsof each of the tubes 144 and 145.

A bottom aperture 148 is formed in the end of the tube 144 and oppositethe mirror 138 to permit the passage of the arc image rays 125 from thecrucible 22 disposeiig It will be appreciated that rotation of thepinion by means of the hand knob 179 will cause the tube 156 therebelow.The first mirror 138 redirects the rays 125 in a direction parallel tothe axis of the tubes 144 and 145 through the lens 140 and onto themirror 139 which, in

' tube 144.

The aperture 150 adjacent the mirror 139 is recessed at 155 forreceiving the lower end of a vertical tube 156 to which the mirrorsupport tube 145 is suitably aflixed in a sealing relation. The bore 158of the tube 156 is coaxial with the opening 150 to permit the passage ofthe arc image rays 125 from the mirror 139 to the prism 142. Thevertical tube 156 extends through an aperture 160 in the base plate 133and terminates at its upper end in an outwardly extending flange 161.The lower surface of the flange 161'is suppor:ed by an annular bearingring 163 which surrounds the tube 156 and is disposed in a circularrecess 164 formed in the upper surface of the base plate 133. A collar166 surrounds the tube 156 below the base plate 133 and is held inpositionby a set screw 167 to prevent upward movement of the tube 156relative to the I base plate 133.

- for rotation in an aperture 174 formed in the upper surface of thebase plate 133 and which extends upwardly through an aligned aperture175 forined in an inverted L-shaped pinion holder 177 suitably aflixedto the base plate 133. A hand knob 179 is aflixe d to the upper endotthe sh'aft172 so that the pinion 171 may be rotated in eitherdirection.

A cover glass 180 is secured over the upper end of the tube 156 by aglass cap 182 which is aflixed tothe flange 161 by screws 184'and' whichhas an aperture 183 coaxialwith the axis of the tube 156.

The prism 142 which is of the total reflecting type is secured to aprism mount 186 by aprism frame 187. The prism mount 186 has a centralaperture 189, which is fixedly positioned above the bore of the tube 156by a prism support bracket 190 rigidly aflixed to the base plate torotate about its axis. This, in turn, will move the mirror 138 and theopening 148 in the tube 144 in a circular path about the axis of tube156, as indicated by phantom lines in FIG. 2. This allows the mirror 138to be moved relative to the inner surface of the crucible as, forexample, between the position shown by full lines in FIG. 4 to theposition shown by dotted lines. In this manner, the mirror may be placedin a position as close as possible to the electrodesouter surface toview the arc, taking into consideration discontinuities in theelectrodes outer surface. In addition, when a smaller diameter electrode46' is employed'as shown by phantom lines in FIG. 4 the mirror 138 maybe rotated into a correspondingly close position relative to such anelectrode. Regardless of the position of the mirror 138, however, itwill'always face the mirror 139 so that the electrode image ray 125 I12.1 and the mirror assembly 122 associated with each of 6 the opticalassemblies 120, is mounted on a horizontal plate 194, which is supportedon the-member 64 by a bracket 195. Support member 64 is suitablyapertured at 197 to permit the arc image ray.125 to pass front theplrisms 142 to their associated lens 122 and mirrors assentb y 121.

As seen in FIGS. 4 and 5, the arc image rays from each side of theelectrode pass upwardly to the first mirror 138 where they are reflectedbackwardlyonto the second mirror 139, for redirection upwardly to theprism 142, which in turn reflects them through their associated .lens122 and mirror assembly 121 and then through the lens 123 to theoperator viewing screen 124.

Each mirror assembly 121 is shown more particularly in FIG, 6 to includea three sided housing 200 having side walls 202 and 203 and a back wall206 which is pivotally mounted between an open position shown in FIG. 6and a closed position. The sidewalls 202 and 203 of housing 200 arepreferably of substantially equal areas and each has an enlargedaperture 205 formed therein.

sembly. 13 pivots, which is 90 in the illustrated embodiment. Thebackwall is equiangularly disposed relative to each of the sidewalls 202and 203 and this angle is 45 in the illustrated embodiment.

A mirror 207 is atfixed to the inner surface of the closure cover 206.It will be appreciated that when the backwall 206 is open, light raysentering either of the apertures 205 will pass out of the openback ofthe housing 200. However, when the back wall 206 is in a closedposition, light rays entering one of the apertures 205 J tion over thefirst crucible 22, as shown by full lines inFIG. 4, each of the openings204 and prisms 142 are also in' alignment with its respective lens 123.However,

when the electrode drive assembly 13 is pivotcdto its" position over thealternate crucible 22', as shown by.-

phantom lines in FIG. 4,v the optical center line of each prism andopening 204 is displaced from that of their associated lens 123 by anangle equal to the .angle through which the drive-assembly'13 pivots.For this reason, the arc image rays must be redirected through an angleequal to the complement of the pivoted angle. This result is achievedbythe angular arrangement of the walls 202,

.203 and 206 of the housing 200.

When the electrode drive assembly 13, which-carries the opticalassemblies 120, is in a position over thefirst crucible 22, each of thebackwalls 206 of the housings 200 is open so that the arc image rays 125pass through the openings 204 and out of the open backs of the housings200 to the lens 123 and the operator viewing screen 124. However, whenthe electrode drive assembly is pivoted to a position above thealternate crucible 22', as shown by phantom lines in FIG. 4, thebackwalls 206 of the housings 200 are closed, so that the mirror 121 isopposite the apertures 204 and 205. When in this position, aperture 204is in alignment with the prism 142 while aperture 205 is in alignmentwith the lens 123. As a result, the are image rays from the prisms 142will enter the 7 metrically opposite sides of the pivotal axis and liealong a line angularly displaced relative to the arc image rays E35 byan angle which is one-half of the complement of the pivotal angle. Inthe illustrated embodiment the assembly illustrated pivots 90 so thatthe minor astcntblics lie along a line displaced 45 from the arc imagerays 125.

it will be seen that the optical system according to the instantinvention permits the arc to be viewed on a. single ttttor viewingscreen even when the electrode drive mbly is pivoted from a positionover a first crucible .2 to a position over a second, or alternate,crucible 22'.

It will also be appreciated that if the pivotal angle of the electrodedrive assembly is other than 90, the angles between the walls 202 and203 and the closure 206 of the housing 200 will have to be adjustedaccordingly.

While only a single embodiment of the instant invention has been shownand described, it is not intended to be limited thereby but only by thescope of the appended claims.

i claim:

1. In an arc melting furnace, the combination of a plurality of vessels,support means, electrode drive means mounted on said support means forsupporting an electr do in said vessels, said support means beingmovable from a fi'st position above one of said vessels'to a secondposition above another of said vessels, an optical system includinglight modifying means mounted on said electrode drive means andconstructed and arranged to receive an electric arc image ray and toproject said ray at a -edetermined angle, viewing means disposed forreing said projected ray when said electrode drive mechanism is in itsfirst position, reflecting means positioned to receive said projectedrays when said electrode drive mechanism is in its second position, saidreflector =ing disposed in such an angular position relative to said tmodifying means and said viewing means that'the projected rays willreflected to said viewing means.

in an arc melting furnace, the combination of a piurality of vesselseach adapted to receive an ingot ned by the melting of a consumableelectrode therein, ure means selectively engageable with the upper endsof said vessels, an electrode drive mechanism extending through saidclosure means for supporting an electrode in said vessels, and means formoving said electrode drive mechanism from a first position above one ofsaid vessels to a second position above another of said vessels, anoptical system including light modifying means mounted on'said electrodedrive means and constructed and arranged to receive an electric arcimage ray and to 'ect said ray at a predetermined angle, viewing meanssed for receiving said projected ray when said elec- "cirdrive mechanismis in its first position, reflecting us mounted on said electrode drivemechanism and tioned to receive said projected rays when saidelecitutlt. drive mechanism is in its second position, said t".;llt?ClOIbeing disposed in such an angular position relative to said lightmodifying means and said viewing means that the projected rays will bereflected onto said viewing Ill iiS.

. In an arc melting furnace, the combination of a g inrality of vessels,support means, an electrode drive in its first position, reflectingmeans mounted on said sctrode drive mechanism and being movabletherewith,

aid reflecting means being positioned to receive said pro- 1 .d rayswhen said electrode drive mechanism is in mounted on said means forsupporting an electrode in each of its first and second positions, saidreflecting means also being movable relative to said drive mechanismbetween an operative position which is effective to reflect .said raysand an inoperative position in which it s ineffective to reflect saidrays, said reflector being disposed in such an angular position relativeto said light modifying means and said viewing means that the projectedrays will be reflected at an angle which is a complement of the anglethrough which said electrode drive mechanism pivots from its first toits second positions.

t. In an arc melting furnace, the combination of a plurality of vessels,support means, an electrode drive mechanism mounted on said supportmeans for supporting an electrode in said vessels, said support meansbeing movable from a first position-above one of said vessels to asecond position above another of said vessels, an optical systemincluding light modifying means mounted on said electrode drive meansand constructed and arranged to receive an electric arc image ray and toproject said ray at a predetermined angle, viewing means disposed forreceiving said projected ray when said electrode drive mechanism is inits first position, reflecting means pivotally mounted on said supportmeans and being movable therewith, said reflecting means beingpositioned to receive said projected rays when said support means is ineach of its first and second positions, said reflecting means also beingmovable relative to said support means between an operative positionwhich is effective to reflect said rays and an inoperative position inwhich it is ineffective to reflect said rays, said reflecting meansbeing disposed in such an angular position relative to said lightmodifying means and said viewing means when said electrode drivemechanism is in its second position that the projected rays will bereflected to said viewing means.

5. In an arc melting furnace, the combination of a plurality of vesselseach adapted to receive an ingot formed by the melting of a consumableelectrode therein, frame means constructed and arranged to be movedhorizontally from a first position above one vessel to a second positionabove another vessel, closure means carried by said frame means andselectively engageable with the upperends of said vessels, an electrodedrive assembly mounted on said frame means and extending through saidclosure means for supporting an electrode in said vessels, an opticalsystem including light modifying means mounted on said frame means andconstructed and arranged to receive an upwardly directed electric arcimage ray and to project said ray at a predetermined generallyhorizontal direction, viewing means disposed for receivingv saidprojected ray when said frame means is in its first position, reflectingmeans pivotally mounted on said frame means and being movable therewith,said reflecting means being positioned between said light modifyingmeans and said viewing means when said electrode drive mechanism is inits first position, said reflecting means being pivotable relative tosaid frame means between an operative position in which it is effectiveto reflect said rays and an inoperative position in which it isineffective to reflect said rays, said reflector being disposed in suchan angular position relative to said light modifying means and saidviewing screen that said projected rays will be reflected at an anglewhich is a complement of the angle through which said frame means pivotsfrom its first to' its second positions.

6. In an arc melting furnace, the combination of a plurality of vesselseach adapted to receive an ingot formed by the melting of a consumableelectrode therein, frame means constructed and arranged to be movedhorizontally from a first position above one vessel to a second positionabove another vessel, closure means carried by said frame means andselectively engagcable with the upper ends of said vessels, an electrodedrive assembly mounted on said frame means and extending through saidclosure means for supporting an electrode in said vessels, an opticalsystem including a pair of light modi- 9 fying means mounted on saidframe means in spaced re-= lation on the opposite sides of saidelectrode drive as sembly and each being constructed and arrangedto'receive an upwardly directed electric arc image ray and to projectsaid rays at the same predetermined generally hori zontal direction, aviewing screen disposed for receiving said projected rays when saidframe means is in its first position, first and second reflecting meansmounted on said frame means and being movable therewith, each of saidreflecting means being positioned between one of said light modifyingmeans and said viewing screen when said electrode drive mechanism is inits first position, each of said reflecting means being pivotable relative to said frame means between an operative position in which each iseffective to reflect the projected rays from a different one of saidlight modifying means and an inoperative position in which each isineffective to reflect said rays, each of sad reflectors being disposedon such an angular position relative to said light modifying means andsaid viewing screen that said projected rays will be reflected at anangle which is a complement of the angle through which said frame meanspivots from its first to its second positions.

7. In an electric arc furnace, the combination of a vessel adapted toreceive molten metal, support means engageable with said vessel,electrode means carried by said support means for supporting anelectrode in said vessel, optical assembly means mounted on said supportmeans for rotation about an axis generally parallel with said electrodemeans, said optical assembly including tube means disposed at apredetermined angle relative to said rotational axis and having lightmodifying means constructed and arranged for receiving light rays fromsaid are and for projecting said rays along the axis of tube means,second light modifying means fixedly mounted on said support means anddisposed for receiving said light rays and for redirecting said lightrays through a preselected angle,

8, In an electric arc furnace, the combination of a vessel adapted toreceive molten metal, closure means selectively engageable with theupper end of said vessel, an electrode drive mechanism extending throughsaid closure means for supporting an electrode in said vessel, opticalassembly means mounted on said closure means for rotation about avertical axis and disposed adjacent said electrode drive mechanism, saidoptical assembly including tube means disposed at a predetermined anglerelative to said rotational axis and having light modifying means at itsouter end and constructed and arranged for receiving upwardly directedlight rays from said are and for projecting said rays along the axis oftube means, second light modifying means fixedly mounted on said closuremeans and disposed for receiving said light rays and for redirectingsaid light rays through a preselected angle 9 In an electric arcfurnace, the combination of a vessel adapted to receive molten metal,support means, an electrode drive mechanism extending mounted on saidsupport means for supporting an electrode in said vessel, an opticalassembly mounted on said support means and adjacent said electrode drivemechanism, said optical as sembly including first tube means extendinggenerally parallel with said electrode, second elongate tube meansaffixed to said first tube means and extending generally transverselythereto, first light modifying means mounted in said second tube meansand disposed for receiving light rays directed parallel to saidelectrode and for redirecting said light rays along the axis of secondtube means, second light modifying means disposed at the juncture ofsaid first and second tube means and oriented for receiving light raysdirected along the axis of said second tube means and for redirectingsaid rays along the axis of said first tube means, means for rotatingsaid first tube means about its axis so that said first reflecting meansis moved and relative to said electrode, and third light modifying meansfixedly mounted on said support means and disposed for receiving lightrays which are directed along the axis of said first tube means andbeing operable to redirect rays through a preselected angle 10, In aconsumable electrode arc melting furnace, the combination of a vesseladapted to receive an ingot. formed by the melting of a consumableelectrode therein, support means above said vessel, an electrode drivemechanism mounted on said support means and extending vertically forsupporting an electrode in said vessel, an. optical assembly mounted onsaid support means adjacent. said electrode drive mechanism, saidoptical assembly including first tube means extending vertically, secondtube means affixed to said first tube means and extending generallytransversely thereto, first reflecting means mounted in said second tubemeans and disposed for rereiving upwardly directed light rays and forreflecting said rays along the axis of second tube means, secondrefleeting means disposed at the juncture of said first and second tubemeans and oriented for receiving light rays directed along the axis ofsaid second tube means and for reflecting said rays upwardly along theaxis of said first: tube means, means for rotating said first tube meansabout: a vertical axis so that said first reflecting means is movedrelative to said electrode drive means, and light modifying meansfixedly mounted on said closure means and dis posed above the upper endof said first tube means for receiving light rays directed along theaxis of said first tube means and for redirecting said rays through apre selected anglet 1L In a consumable electrode arc melting furnace,the combination of a vessel adapted to receive an ingot formed by themelting of a consumable electrode therein, clo sure means selectivelyengageable with the upper end of said vessel, an electrode drivemechanism extending through said closure means for supporting anelectrode in said vessel, an optical assembly mounted on said closuremeans and adjacent said electrode drive mechanism, said optical assemblyincluding first elongate tube means ex tending vertically through saidclosure means, second elongate tube means aflixed to the lower end ofsaid first tube means and extending normally relative thereto, firstreflecting means disposed at the outer end of said second tube means anddisposed for receiving upwardly directed. light rays and for reflectingsaid rays along the axis of second tube means, second reflecting meansdisposed at the juncture of said first and second tube means andoriented for receiving light rays directed along the axis of said secondtube means and for reflecting said rays up= wardly along the axis ofsaid first tube means, manually operable means for rotating said firsttube means about its axis so that said first reflecting means is movedin a circu- 'lar path and relative to said electrode drive means, andlight modifying means fixedly mounted on said closure means and disposedabove the upper end of said first tube means for receiving light raysdirected along the axis of said first tube means and for redirectingsaid rays through a preselected angle.

12, In a consumable electrode arc melting furnace, the combination of avessel adapted to receive an ingot: formed by the melting of aconsumable electrode therein, closure means selectively engageable withthe upper end of said vessel, an electrode drive mechanism extendingvertically through said closure means for supporting an electrode insaid vessel, an optical assembly mounted on said closure means andadjacent said electrode drive mechanism, said optical assembly includingfirst elongate tube means extending vertically through said closuremeans in substantial parallelism with said electrode drive means, secondelongate tube means having one end affixed to the lower end of saidfirst tube means and ex-' tending normally relative thereto, an openingadjacent: the other end of said second tube means and facing down wardlytoward said vessel, first reflecting means disposed adjacent: the otherend of said second tube opposite the opening therein for receivingupwardly directed light :rays and for reflecting said rays along theaxis of second tube means, second reflecting means disposed at thejuncture of said first and second tube means and oriented for receivinglight rays directed along the axis of said second tube means and forreflecting said rays upwardly along the axis of said first tube means,manually operable means for rotating said first tube means about avertical axis so that said first reflecting means is moved a circularpath and relative to said electrode drive means, and reflecting prismmeans fixedly mounted on said closure means and disposed above the upperend of said first tube means for receiving light rays directed along theaxis of said first tube means and for reflecting said. rays through apreselected angle.

13 In an electric arc furnace, the combination of a plurality ofvessels, support means constructed and arranged to be moved horizontallyfrom a first position above one vessel to a second position aboveanother vessel, optical assembly means mounted on said support means forrotation about a vertical axis and disposed ad" jacent said electrodedrive mechanism, said optical assembly including tube means disposed ata predetermined angle relative to said rotational axis, first lightmodifying means at the outer end of said tube means and constructed andarranged for receiving upwardly directed light rays from said are andfor redirecting said rays along the axis of tube means, second lightmodifying means fixedly mounted on said frame means and disposed forreceiving said light rays and for projecting said light rays through apreselected angle, viewing means dis posed for receiving said projectedrays when said electrode drive mechanism is in its first position,reflecting means mounted on said frame means and being movabletherewith, said reflecting means being positioned to refleet saidprojected rays and being movable relative to said frame means between anoperative position in which it is effective to reflect said projectedrays and an inoperative position in which it is ineffective to reflectsaid rays, said reflecting means being disposed in such an angularposition relative to said second light modifying means and said viewingmeans when said frame means is in its second position that saidprojected rays will be re flected to said viewing means.

14. In an electric arc furnace, the combination of a plurality ofvessels, frame means constructed and arranged to be moved horizontallyfrom a first position above one vessel to a second position aboveanother vessel, closure means carried by said frame means andselectively engageable with the upper ends of said vessels, an electrodedrive mechanism mounted on said frame means and extending through saidclosure means for sup porting an electrode in said vessels, an opticalassembly mounted on said closure means and adjacent said electrode drivemechanism, said optical assembly including first tube means extendingvertically through said closure means in substantial parallelism withsaid electrode drive means, second tube means having one end affixed tothe lower end of said first tube means and extending normal- .lyrelative thereto, first reflecting means disposed adjacent the other endof said second tube means for receiving up- Wardly directed light raysand for reflecting said rays along the axis of second tube means, secondreflecting means disposed at the juncture of said first and second tubemeans and oriented for receiving light rays directed along the axis ofsaid second tube means and for reflect ing said rays upwardly along theaxis of said first tube means, manually operable means for rotating saidfirst tube means about a vertical axis so that said first reflectingsaid projected rays when said electrode drive means and light modifyingmeans fixedly mounted on said frame means and disposed above the upperend of said first tube means for receiving light rays directed along theaxis of said first tube means and for projecting said rays through apreselected angle, viewing means disposed for receiving said projectedrays when said electrode drive mecha nism is in its first position,reflecting means mounted on. said frame means and being movabletherewith, said re flecting means being positioned to reflect saidprojected rays and being movable relative to said frame means andbetween an operative position in which it is effective to reflect saidprojected rays and an inoperative position in which it is ineffective toreflect said rays, said reflector being disposed in such an angularposition relati e to said light modifying means and said viewing meanswhen said frame means is in its second position that said projected rayswill be reflected to said viewing means,

15., In an arc melting furnace, the combination of a plurality ofvessels each adapted to receive an ingot formed by the melting of aconsumable electrode therein, frame means constructed and arranged to bemoved horizontally from a first position above one vessel to a secondposition above another vessel, closure means carried. by said framemeans and selectively engageable with the upper ends of said vessels, anelectrode drive mechanism. mounted on said frame means and extendingthrough said closure means for supporting an electrode in said vessels,an optical assembly mounted on said closure means and adjacent saidelectrode drive mechanism, said optical assembly including firstelongate tube means extending vertically through said closure means insubstantial parallelism with said electrode drive means, second elongatetube means having one end affixed to the lower end of said first tubemeans and extending normally relative thereto, an opening adjacent theother end of said second tube means and facing downwardly toward saidvessel, first reflecting means disposed adjacent the other end of saidsecond tube opposite the opening therein for receiving upwardy directedlight rays and for re-- flecting said rays along the axis of second tubemeans, second reflecting means disposed at the juncture of said firstand second tube means and oriented for receiving light rays directedalong the axis of said second tube means and for reflecting said raysupwardly along the axis of said first tube means, manually operablemeans for rotating said first tube means about a vertical axis so thatsaid first reflecting means is moved in a circular path and relative tosaid electrode drive means, and reflecting prism means fixedly mountedon said frame means and disposed above the upper end of said first tubemeans for receiving light rays directed along the axis of said firsttube means and for reflecting said rays through a pre selected angle, aviewing screen disposed for receiving said projected rays when saidelectrode drive mecha nism is in its first position, reflecting meansmounted on said frame means and being movable therewith, said reflectingmeans being positioned between said light modifying means and saidviewing screen when said frame means is in its first position, saidreflecting means being pivotable relative to said frame means between anopera tive position in which it is eflective to reflect said projected.rays and an inoperative position in which it is inelfective to reflectsaid rays, said reflector being disposed in such an angular positionrelative to said light modifying means and said viewing screen that saidprojected rays will be reflected at an angle which is a complement ofthe angle through which said frame means pivots from its first to itssecond positions References Cited UNITED STATES PATENTS BERNARD A,GILHEANY, Primary Examiner;

B, GILSON, A ssistant Examinien

1. IN AN ARC MELTING FURNACE, THE COMBINATION OF A PLURALITY OF VESSELS,SUPPORT MEANS, ELECTRODE DRIVE MEANS MOUNTED ON SAID SUPPORT MEANS FORSUPPORTING AN ELECTRODE IN SAID VESSELS, SAID SUPPORT MEANS BEINGMOVABLE FROM A FIRST POSITION ABOVE ONE OF SAID VESSELS TO A SECONDPOSITION ABOVE ANOTHER OF SAID VESSELS, AN OPTICAL SYSTEM INCLUDINGLIGHT MODIFYING MEANS MOUNTED ON SAID ELECTRODE DRIVE MEANS ANDCONSTRUCTED AND ARRANGED TO RECEIVE AN ELECTRIC ARC IMAGE RAY AND TOPROJECT SAID RAY AT A PREDETERMINED ANGLE, VIEWING MEANS DISPOSED FORRECEIVING SAID PROJECTED RAY WHEN SAID ELECTRODE DRIVE MECHANISM IS INITS FIRST POSITION, REFLECTING MEANS POSITIONED TO RECEIVE SAIDPROJECTED RAYS WHEN SAID ELECTRODE DRIVE MECHANISM IS IN ITS SECONDPOSITION, SAID REFLECTOR BEING DISPOSED IN SUCH AN ANGULAR POSITIONRELATIVE TO SAID LIGHT MODIFYING MEANS AND SAID VIEWING MEANS THAT THEPROJECTED RAYS WILL REFLECTED TO SAID VIEWING MEANS.